Traditionally, a television (“TV”) signal is received on one wire, e.g., cable TV, or a terrestrial antenna. A telephone signal is received on a separate signal transmission medium, e.g., the plain old telephone system (“POTS”), and the Internet has been available on either of these “systems”. Both cable operators and telephone company operators are beginning to offer all three system services on one connection, which is commonly referred to as “triple play” and is used by service operators to describe the bundling of telephony, data and video down a single connection.
Internet Protocol Television (“IPTV”) describes a system where a digital television service is delivered using the Internet Protocol (“IP”) over a network infrastructure, which may include delivery by a broadband connection. Broadband in telecommunications is a term which refers to a transmission method which includes or handles a relatively wide range of frequencies which may be divided into channels or frequency bins. Broadband is a relative term, understood according to its context. The wider the bandwidth, the more information that can be carried. In radio, for example, a very narrowband signal can carry Morse code; a broader band can carry speech; a yet broader band is required to carry music without losing the high audio frequencies required for realistic sound reproduction. A television antenna described as “normal” may be capable of receiving a certain range of channels; one described as “broadband” can receive more channels.
In data communications, a voiceband modem will transmit a bit rate of 56 kilobits per seconds (kbit/s) over a telephone line; over the same telephone line a bit rate of several megabits per second can be handled by a DSL broadband modem, which is described as broadband (relative to a voiceband modem over a telephone line, although much less than can be achieved over a fiber optic circuit, for example). For residential users, IPTV is often provided in conjunction with video on demand (“VoD”) and may be bundled with Internet services such as Web access and voice over Internet Protocol (“VoIP”). IPTV is typically supplied by a broadband operator using a closed network infrastructure. This closed network approach is in competition with the delivery of TV content over the public Internet. This type of delivery is widely called TV over Internet or Internet Television. In businesses, IPTV may be used to deliver television content over corporate LANs and business networks.
Digital subscriber line (“DSL”) is a family of technologies that provide digital data transmission over the wires of a local telephony network. DSL communication links are distance sensitive-technology and thus as the connection's length increases, the signal quality decreases and the connection speed is reduced. In general, DSL communication links are limited in download (from the carrier central office to the DSL modem) bit rate according to the loop length and the amount of noise on the line to a value of up to 25 Mb/s or less. Upload (from the DSL modem to the carrier central office) speed is lower than download speed for asymmetric digital subscriber line (“ADSL”) and equal to download speed for symmetric digital subscriber line (“SDSL”).
IPTV and video services require substantial bit rate and a value of 25 Mb/s might be insufficient for some users in a given service area. However, video is often variable in bit rate, as are various other services. Therefore, for most of the time the capacity of the DSL link is sufficient, but during particular “bursty” moments the capacity of the single link is not sufficient. In such a case, it would be advantageous to have a second, shared link which can be used during those periods of time when the capacity of the DSL link is exceeded.
One approach to resolve this problem is to add a second DSL line and employ a function called “bonding”. The addition of a second DSL line adds substantial cost, and may not be available in some service areas. Another approach to resolve this problem is adding a fiber link to the premise; however, this too adds substantial infrastructure cost, and may not be available in some service areas. A third approach to resolve this problem is to provide additional compression of the video signal; however, this has resulted in degraded picture quality.
What is desired is an arrangement under which link overload or congestion is managed by routing some communication data from one communication link during an overload or congestion period to a second communication link.